Despite the advent of V-type belt drives and the like, it is still common practice to use large flat belts for driving spindles in machine tools, such as the wheelhead of a grinding machine. This is because the flat belt provides the maximum area of contact between the belt and the spindle and thin flat belts can operate at much higher surface speeds than V-belts. However, the conventional crowned pulley provides some disadvantages when used with a flat belt. While the belt is dry it operates well with the pulley, but there are occasions when the belt becomes saturated with fluid, as is sometimes the case when mist lubrication is used in a machine tool or oil is used as a grinding coolant. Under such conditions it is often found that the belt slips off the end of the pulley and renders the machine tool inoperative. While it is not a difficult matter to remove the shield from the machine and replace the belt, nevertheless, an expensive machine is not productively occupied during this "down-time" and this is economically unsound since a piece of valuable capital equipment is not being used effectively. These and other difficulties experienced with the prior art devices have been obviated in a novel manner by the present invention.
It is, therefore, an outstanding object of the invention to provide a pulley constructed so that a flat belt will remain on the pulley irrespective of whether the belt is wet or dry.
Another object of this invention is the provision of a pulley whose surface is of such a conformation that it has a portion of its surface particularly adapted for use with a dry flat belt and another portion particularly adapted for use when the belt is wet.
A further object of the present invention is the provision of a pulley which will not release a flat belt even when the belt is covered with lubricant.
It is another object of the instant invention to provide a pulley which is simple in construction, inexpensive to manufacture, and which is capable of a long life of useful service under varying conditions with a minimum of maintenance.
With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.